Lubricating oil additive and method of preparing the same



U Q d S P O 2,822,332 I11t (81:65 21tl1t C Patented Feb 4, 1958 I havediscovered that an additive having detergent and corrosion inhibitingproperties can be easily prepared 2,822,332 from inexpensive startingmaterials and which can bi;

incorporated in lubricating oils to form compositions o r ggg g gi gE FJ 5 improved lubricating oil characteristics. The process of thisinvention comprises heating a hydrocarbon fraction Richard S. Logan,Bartlesville, @kla, assignor to Phillips with sulfur. In order that thereaction may be effected Petroleum Company, a corporation of Delawaremost efficiently, the sulfur is preferably finely divided. For thetreatment, the temperature shouldpreferably be No gi' 3 22; 2:? 1954 10at least 300 P. so that the reaction may be carried out in a practicallength of time. The temperature generally 6 Claimsused is in excess of400'F. There appears to be no advantage in the use of temperatureshigher than 600 F. although I have used a temperature as high as 700 F.This invention relates to a lubricating oil additive andSuperatmospheric pressures are generally used although a method ofpreparing lubricating oil additives. In a the range of 10 to 200 p. s.i. a. can be set forth as suitable. further aspect, this inventionrelates to petroleum lubricat- The additives of this invention can beprepared from ing oil compositions. In a further aspect this inventionhydrocarbon material containing at least 40 carbon atoms relates to anadditive which has detergent and corrosion per molecule. The materialsshould have a refractive inhibitive properties prepared by treating ahydrocarbon index of between 1.440 and 1.525. In addition topetrofraction with sulfur. leum fractions, hydrocarbon materials whichcan be used As the speed and output of internal combustion enincludesubstantially saturated diene polymers, such as gines have increased tohigher and higher values, the polybutadiene and polypentadiene andpolymers of oleability of hydrocarbon oils to maintain an engine free Ffins having from 2 to 12 carbon atoms per molecule such from lacquer,sludge and carbon deposits has decreased. as polypropylene,polyethylene, polyisobutylene, etc., Under present day conditions,lubricating oils for use in preferably having a ratio of carbon atoms toolefin bonds automotive and diesel engines require use of additive of atleast 40 to 1 and not less than to 1, copolymers agems Which havedetergent and corrosion inhibiting such as styrene-olefin copolymers,alkylated polystyrene, properties. Also, stop and go driving in coldweather etc. Another way of stating this unsaturation is to say has atendency to produce sludge in a lubricating system 30 that thehydrocarbons have a maximum iodine number and additives are used tocombat this problem. of approximately 60 and it is preferably belowapproxi- The requirements necessary for a satisfactory detergent mately45. additive are: (l) compatibility with lubricating oil and Petroleumfractions which contain substantially no other additives which may bepresent; (2) maintenance asphalt either in a natural state or whendeasphalted, and of satisfactory cleanliness of engine P P p y in whichhave been solvent extracted to reduce the content h g belt Zone of the Pand Chemical inertof aromatic-type hydrocarbons therein and which haveHess With respect to supplemental addiiiVes and metal been dewaxed, arealso suitable. These include lubricatgine parts. Additional desirablecharacteristics include: ing oils produced from Pennsylvania,Mid-Continent, ease of handling, as such or as an l eoncen- California,East Texas, Gulf Coast, Venezuela, Borneo, irate; minimum effect 011 OilP P such as and Arabian crudes. The source of the crude from which y,6010i and Oder; low Overall 60st; and the petroleum fraction is deriveddoes not significantly independence With respect in Critically limitedor P influence the. preparation or properties of the detergent sive rawmaterials. material of my invention, provided the petroleum frac- Theuse Of additives in lubricating Compositions as tion has been preparedby subjecting the crude to certain I inhibitors, eXidaiiOn inhibitors,Viscosity index necessary treatment to extrude certain undesirablemateimprovers, dispersing agents, pour-point depressants, exi l th fiIeme Pressure agents, lubricity imPTOVeIS and ash form- In thepreparation of the preferred petroleum fraction g detergents, is WellknOWn- The need for additives from which the detergent material of thisinvention is to imPlTWe Various Specific Properties of lubricating Oilsproduced, a crude oil is topped, i. e., distilled to remove is acute andnecessary because of the severe conditions to therefrom th o olatile,lower molecular weight hywhich lubricating oils are exposed. In internalcombusd a bons, such as gasoline and light gas oil, and then tionengines it is desirable that the lubricating P vacuum reduced to removeheavy gas oil and light lubritions be resistant to sludge and Varnishformation and, in eating n f the SAE 1 and 20 viscosity grade The theevent f such formations, to Prevent the deposition uum reduced crude isthen propane fractionated to remove of these materials on the metallicparts of the engines. an overhead fr ti f about 100 SUS at 210 R 1 Eachof th j ts of this invention Will be Obtained cosity and the residualmaterial is subjected to a second y at least one of the aspects of thisinvention propane fractionation to remove another overhead frac- AnObject of hi invention is to Provide a new lubncat' tion of about 200SUS at 210 F. viscosity. The residue g Oil additivefrom the secondfractionation may be subjected to a A further Object of this. Invention18 provlde third propane fractionation to remove still anotherovermethod of Pmducing the lmPmved addltlves head fraction of about 575SUS at 210 F. viscosity. Proinvention. e of A further object of thisinvention is to provide an un- 53 ;?figggg g i g g g 332 2 315 2 22; gfproved lubricating oil utilizing an additive derived from petroleum.

Other and further objects of this invention Wlll be apparent to oneskilled in the art upon studying the accompanying disclosure.

Following the propane fractionation step, the overhead oil fraction issolvent extracted with a selective solvent which will separate theparafiinic hydrocarbons from the aromatic-type hydrocarbons.

Suitable selective solvents for aromatic hydrocarbons include amongothers, the various phenols, sulfur dioxide, furfural andflfi-dichlorodiethyl ether. This solvent extraction step for the removalof the more highly aromatic compounds can be carried out in accordancewith well-known concurrent or countercurrent solvent extractiontechniques, as well as by the Duo-Sol technique.

The resulting solvent extracted material, before or after the removal ofthe more aromatic hydrocarbons, is preferably dewaxed. Dewaxing may becarried out by any conventional method, e. g., by solvent dewaxing usingpropane or solvent mixtures, such as methyl ethyl ketone or methylisobutyl ketone with benzene at a suitable temperature.

1 Each fraction of the phenol extracted, dewaxed, propane-fractionatedoil can be used in preparing the detergent material of this inventionwith good results but the oil fraction from the second propanefractionation is preferred. It will be recognized by those skilled infl1e art that propane fractionated oils differing from thosedescribedmay be used or a single broad viscosity out can be used. Theresidual material from the final propane fractionation contains therejected asphalt and more aromatic oils.

Although the preferred method for preparation of feed stock is as abovedescribed, other methods may be used to secure a similar typehydrocarbon fraction. Thus, a vacuum reduced crude which has essentiallyno asphalt, such as a Pennsylvania oil, may be used directly or after alight acid treatment. Another method, while not feasible commercially atthe present time, is ultra-high vacuum (molecular) distillation toobtain the desired fraction.

As pointed out above, a polydiene, such as liquid polybutadiene which isprepared by sodium-catalyzed polymerization of butadiene and whichmaterial is subsequently hydrogenated so as to reduce the olefinicunsaturation thereof to the desired amount, is another suitable feedstock for use in the production of the detergent material of thisinvention. When butadiene is polymerized, only one double bond remainstherein for each butadiene group of the polymer. The feed material ofthis invention should be hydrogenated sufliciently so that the ratio ofcarbon atoms to double bonds is at least 30 to 1. Preparation of liquidpolybutadiene may be carried out by means of the process set forth in U.S. Patent No. 2,631,175, issued March 10, 1953, by W. W. Crouch.

Another suitable feed stock is a liquid or semi-solid polybutadienewhich is prepared by conventional emulsionpolymen'zation and coagulationto form synthetic rubber, subsequently hydrogenating said material so asto reduce the olefinic unsaturation thereof to the desired amount andfinally thermally depolymerizing it to increase the oil solubility.

Another suitable feed material is a high molecular weight polymerprepared by zirconium tetrachloride polymerization of propylene. Stillanother material which has proved to be useful as a feed material in thepreparation of the detergent material of this invention is a tackypolymer prepared by the polymerization of propylene overchromia-silica-alumina catalyst, as more fully disclosed in U. S.application Serial No. 333,576, filed January 23, 1953, now abandoned,by John P. Hogan and Robert L. Banks. Another suitable feed material 18a copolymer of styrene with olefins in which the olefin portionconstitutes at least SOpercent of the total molecular weight of themolecule. With any of these feed materials, it is desired to reduce theamount of olefinic unsaturation to such an extent that the ratio ofcarbon atoms to olefinic bonds is preferably at least 40:1 and not lessthan 30:1.

The hydrocarbon stocks which are useful in the practice of thisinvention include those materials which are identifiable as having thefollowing properties set forth in Table I. i

TABLE I Property Broad Preferred Range Range Refractive Index no 1.440-1. 525 1. 480-1. 515 Average Molecular Weight Above 600 650-10, 000Minimum Molecular Weight of a Component 450 Viscosity, SUS at 210 FAbove Above Viscosity Index (when determinable 50-130 75-125 Carbon AtomContent per Molecule (Ave) Above 40 50-720 1 Viscosity index notdeterminable for non-Newtonian materials.

Table II sets forth the properties of lubricating oils which arepreferred for use in my invention.

The amount of sulfur is generally used in an amount of 5 to 20 weightpercent based upon the weight of the hydrocarbon fraction. The sulfur isusually added in small increments and the hydrocarbon is preferablyagitated during this addition. The addition of sulfur and heating iscontinued until a noticeable increase in viscosity, measured in SayboltUniversal seconds at 210 F., is obtained. This viscosity increase shouldbe at least 1.5 fold at this temperature and can go as high as 50 fold.This viscosity increase is generally in the range of 1.5 to 10 fold andthe range of 1.5 to 2 fold has been found especially valuable with somestock.

The time for this viscosity increase depends upon the temperature but,it may be said, that a time of 2 to 20 hours is usually suitable, theshorter times being associated with higher treating temperatures andvice versa.

For example, using an SAE 250 oil, such an oil coming within thepreferred range set forth in Table II above, sufficient sulfur can beadded so that after the reaction is complete, the sulfurized oil has aviscosity of 300 to 600 SUS at 210 F. Using a temperature of 700 F. andatmospheric pressure, a process time of at least 2 hours is usuallyrequired.

Following completion of the reaction with sulfur, there is anappreciable amount of hydrogen sulfide contained therein. Since it isnot desirable to introduce hydrogen sulfide into an internal combustionengine, the treated material is treated so as to remove this hydrogensulfide.

' This treatment should be continued until the treated bydrocarbonfraction shows no discoloration when in contact with copper. A methodfor hydrogen sulfide removal which I have found satisfactory comprisespassing a gas such as carbon dioxide or natural gas through the treatedstock.

Following removal of hydrogen sulfide, the sulfurized hydrocarbon can beused as an additive without concentration or purification. However, if aproduct of improved quality and purity is desired, the oil containingthe additive is treated with a suitable solvent which is a solvent forthe non-sulfurized fraction but is not a solvent for the additive whichhas combined sulfur therein. Hydrocarbon solvents are preferred. Apreferred method is to treat the sulfurized fraction with propane underpropane fractioning conditions such that a firm plastic or brittle solidis obtained as the insoluble bottom fraction and a propane-solublefraction is obtained as the overhead fraction. The firm plastic orbrittle solid obtained as the bottom fraction is the additiveconcentrate of this invention. This concentrate should contain 2 to 10percent by weight of combined sulfur, although I prefer additives whichcontain 3 to 7.5 percent combined sulfur.

In compounding the improved oil compositions provided by this invention,the additive is added to the desired oil base in an amount sufiicient toobtain the desired degree of improvement in general characteristics ofthe oil. This amount, accordingly, depends upon the characteristics ofthe lubricating oil itself as well as the conditions to which thecomposition is subjected in use. Ordinarily, I employ the additive in anamount representing at least 0.1 percent by weight of the entirecomposition. The amount used seldom exceeds 10 percent by Weight of theentire composition. For a preferred range, amount in the range from 0.3to 5 percent by weight are used. The base oil can be any oil of suitablegrade and viscosity obtained by modern refining methods. The additive ofthis invention functions independent of other additives withoutmaterially altering the physical characteristics of the oil.Accordingly, the oil may contain other additives such as detergents,viscosity index improvers, for dispersing, etc.

In application Serial No. 304,659, filed August 15, 1952, now abandoned,of Whitney, a process of preparing additives having detergent anddispersant properties is disclosed. The process of Whitney comprisesoxidizing a hydrocarbon stock in order to prepare an ashless detergent.The teaching of that disclosure may be combined with my invention, thatis, sulfur can be added to the oil while it is being oxidized accordingto the method of Whitney.

The following examples represent specific embodiments of additivesprepared according to the process of my invention. The amounts,temperatures, times, etc., should be considered as illustrative of theinvention and not as unduly limiting. The neutralization number used inthese examples represents the number of milligrams of potassiumhydroxide required to neutralize 1 gram of the material.

Example I About 7 pounds of a finished SAE 250 stock were charged to areaction vessel equipped with a heating mantle, a thermometer and anagitator. The free space in the reaction vessel was blanketed withnatural gas throughout the treatment. The oil was heated to 480 F. andpowdered sulfur was added in 0.02 pound portions every 10 to 30 minutes.Each addition of sulfur caused considerable foaming with the evolutionof hydrogen sulfide. At the end of 8 hours, 0.44 pound of sulfur hadbeen added. The oil was then stripped of hydrogen sulfide with naturalgas, this taking some 12 hours. After stripping, the viscosity of theoil was 347 SUS at 210 F. the oil showed no discoloration of copperafter 3.5 hours at 180 F. Over a period of 2.5 hours, an additional 0.22pound of sulfur was added and the oil was again stripped of hydrogensulfide for 12 hours. At this time the viscosity was 502 SUS at 210 F.Following stripping for an additional 7 hours the viscosity was 540 SUSat 210 F. The sulfur content was 1.2 percent by weight and theneutralization number was 0.03. A spot test of a lubricatingcomposition, an SAE 30 stock containing the sulfurized oil in aconcentration of 10 percent by weight, gave results indicating excellentdetergency and also oxidation stability.

Example II The sulfurized oil prepared as described in Example I wasadded to a base oil and tested in a high temperature Lauson engine test.The oil employed as a base oil was a solvent-refined Mid-Continent oilof lubricating grade having the following characteristics: Gravity, API30.3 Viscosity at 210 F 61.8 SUS Viscosity index 98 Neutralizationnumber 0.01

The detergent prepared asdescribed in;Example I was added to the baseoil and tested-in a standard Lauson engine. This test consists inplacing 920grams of the oil composition in the crankcase of a singlecylinder Lauson gasoline engine. The engine isoperated under a 1.2 H. P.load at 1600:20'R. P. M. maintaining a cooling jacket temperature of 300R, an :oilt-emperature of 225 F. and anair-to-fuel ratio'of 1-3.5:1.At'the end of 60 hours operation under these conditions the engine isstopped, disassembled, and the piston, crankcase and bearings areexamined. The piston varnish was rated on an arbitrary scale of l to 10with 10 rcpresenting a clean or perfect condition and 1 representing thedirtiest condition.

Results of this test are presented below together with comparative datafor the base oil and base oil plus the commercial oxidation inhibitorSantolube 395X.

Bearing Loss, mg.

Piston Varnish Base Oil Base Oil+0.82 wt. percent 395X. Base 0i1+0.82wt. percent 395K Base Oi1+3.5 wt. percent Sulturized 0 Example IIIALUMINUM BLOCK DATA ON SULFURIZED 250 STOCK 5% Sulfur ized 250 OilTested Base 011 Evaporation loss SUSmu new oil.

SUSwo used Oil--. Vis. increase, SUS Vis. increase, percent Neut. No.new oil Neut. No. used oil Example IV Two additives were prepared, onefrom a Kansas City SAE 20 stock and the second from an SAE 50 stock bytreatment with 2 percent by weight of sulfur for a period of 1 hour at atemperature of 380 to 390 F. During this treatment carbon dioxide wasbubbled through the oil in order to prevent oxidation. The treatedproduct in each case was agitated with a caustic solution of sodiumsulfide to effect removal of free sulfur. The oil was then washed withwater and steamed, the water separated and the oil filtered. A thirdadditive was prepared from an SAE 250 stock according to the method setforth in Example I. These additives were tested in a concentration of3.5 percent by weight in the base oil described in Example II. They weretested according to the method described in Example II in a hightemperature Lauson engine. The following results were obtained:

Cone. Piston Bearing Additive Wt. Varnish Loss,

Percent mg.

None 6. 0 182 From SAE 20 stock 3. 5 5. 7 23. 1 From SAE 50 stock 3. 54. 8 11.9 From SAE 250 stock 3. 5 7. 0 11.2

It to be noted that the additive prepared according to thismvention,that from the 250 stock, was equal to the additives prepared accordingto the method used in preparing the additives from the 20 and 50 stockswith respectto corrosion inhibition. The'additive prepared by the methodof Example I possesses detergent properties while the additives preparedaccording to the other method caused, in one case, a decrease in thepiston varnish rating, and in the other case, substantially the samerating as the base oil.

As many possible embodiments may be made of this invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth is to be interpreted as illustrative and not as undulylimiting the invention. 1

I claim:

l. A process for producing a lubricant additive which comprisessubjecting a petroleum hydrocarbon fraction having the propertiesRefractive index n 1.495-1.515

Average molecular weight 700-900 Viscosity, SUS at 210 F 150-600Viscosity index 80-110 Carbon atom content per molecule 50-70 totreatment with sulfur in an amount of 5 to 20% by Weight based on thehydrocarbon at an elevated temperature sufiicient to increase theviscosity; removing hydrogen sulfide after the reaction is complete; andrecovering an additive having detergent and corrosion inhibitingproperties, said additive containing 2 to 10% by weight of combinedsulfur, being insoluble in propane and having a viscosity at least 1.5times that of the original hydrocarbon.

2. A lubricant additive produced by treating with sul fur a petroleumhydrocarbon fraction having the properties Refractive index nl.495-1.515

Average molecular weight 700-900 Viscosity, SUS at 210 F 150-600Viscosity index 80-110 Carbon atom content per molecule 50-70 at anelevated temperature suflicient to increase the viscosity; said additivebeing insoluble in propane, containing 2 to 10% by weight of combinedsulfur and having a'viscosity of at least 1.5 times that of the originalhydrocarbon.

3. A lubricant composition comprising a major portion of lubricating oiland at least 0.1% by weight of addi- "8 tive produced by treating withsulfur a petroleum hydrocarbon fraction having the properties Refractiveindex n 1.495-1.515

at an elevated temperature sufiicient to increase the viscosity; saidadditive being insoluble in propane, containing 2 to 10% by weight ofcombined sulfur and having a viscosity of at least 1.5 times that of theoriginalhydrocarbon.

4. A process for producing a lubricant additive which comprisessubjecting a propane fractionated SAE 250, solvent extracted petroleumhydrocarbon fraction stock, to treatment with sulfur in an amount of 5to 20% by weight based on the hydrocarbon at a temperature of 300 to 700F. for 2 to 20 hours, the sulfur being added incrementally over the timeof the reaction; removing hydrogen sulfide after the reaction with thesulfur is completed; and recovering a lubricant additive havingdetergent and corrosion inhibiting properties, said additive beinginsoluble in propane, containing 2 to 10% by weight of sulfur and havinga viscosity of at least 1.5 times that of the original hydrocarbon.

5. A lubricant additive produced by treating with sulfur a propanefractionated, SAE 250 solvent extracted petroleum hydrocarbon fractionstock, said additive being insoluble in propane, containing 2 to 10% byweight of combined sulfur and having a viscosity of at least 1.5 timesthat of the original hydrocarbon.

6. A lubricant composition comprising a major portion of lubricating oiland at least 0.1% by weight of an additive produced by treating withsulfur a propane fractionated, 'SAE 250 solvent extracted petroleumhydrocarbon fraction stock, said additive being insoluble in propane,containing 2 to 10% by Weight of combined sulfur and having a viscosityof at least 1.5 times that of the original hydrocarbon.

References Cited in the file of this patent UNITED STATES PATENTS

1. A PROCESS FOR PRODUCING A LUBRICANT ADDITIVE WHICH COMPRISESSUBJECTING A PETROLEUM HYDROCARBON FRACTION HAVING THE PROPERTIES